276 INDUCTION. 



deed, been a matter of great interest at a time w^en the idea of 

 explaining celestial facts by terrestrial laws, was looked upon as the 

 confounding of an iftdefeasible distinction. When, however, the celes- 

 tial motions were accurately ascertained, and the deductive processes 

 performed from which it appeared that their laws and those of teires- 

 . trial gl•a^'ity corresponded, those celestial observations became a set of 

 •instances which exactly eliminated the circumstance of proximity to 

 the earth ; and proved that in "the original case,' that of teirestrial ob- 

 jects, it was not the earth, as such, that caused the motion or the pres^ 

 sure, but the circumstance common to that case with the celestial 

 instances, namely, the presence of some great body within certain 

 limits of distance. 



§ 6. There are, then, three modes of explaining laws of causation, 

 or, which is the same thing, resolving them into other laws. First, 

 when the law of an effect of combined causes is resolved into the sepa- 

 rate laws of the causes, together with the fact of their combination. 

 Secondly, when the law which connects any two links, not proximate, 

 in a chain of causation, is resolved into the laws which connect each 

 with the inteiTnediate links. Both of these are cases of resolving one 

 law into two or more ; in the third, two or more are resolved into one ; 

 when, after the law has been shown to hold good in several different 

 classes of cases, we decide that what is true in each of these classes of 

 cases, is true under some more general supposition, consisting of what 

 all those classes of cases have in common. We may here remark that, 

 this last operation involves none of the uncertainties attendant upon 

 induction by the Method of Agi-eement, since we need not suppose 

 the result to be extended by way of inference to any new class of cases, 

 different fi-om those by the comparison of which it was engendered. 



In all these three processes, laws are, as we hav'e'seen, resolved into 

 laws more general than themselves, laws extending to all the cases 

 which the fonner extend to, and others besides. In the first two 

 modes they are also resolved into laws more certain, in other words, 

 more universally trtie than themselves ; they are, in fact, proved not 

 to be themselves laws of nature, the character of which is to be 

 universally true, but results of laws of nature, Avhich may be only true 

 conditionally, and for the most part. No difference of this sort exists 

 in the third case; since here the partial laws are, in fact, the very 

 same law as the general one, and any exception to them would be an 

 exception to it too. 



By all the three processes, the range of deductive science is 

 extended ; since the laws, thus resolved, may be thenceforth deduced 

 demonstratively from the laws into which they are resolved. As 

 already remarked, the same deductive process which proves a law or 

 fact of causation, if unknown, sei'N'es to explain it when known. 



The word explanation is here used in a somewhat peculiar sense. 

 Wliat is called explaining one law of nature by another, is but sub- 

 stituting one mystery for another; and does nothing to render the 

 general course of nature other than mysterious : we can no more assi'gn 

 a wTiy for the more extensive laws than for the partial ones. The 

 explanation may substitute a mysteiy which has become familiar, and 

 has gi-own to seem not mysterious, for one which is still strange. And 

 this is th^ meaning of explanation, in common parlance. But the 



